Rayon fabric reinforced laminated sheet



Aug. 28, 1962 H. P. FRY, JR

- RAYON FABRIC REINFORCED LAMINATED SHEET Filed Nov. 26, 1958 UnitedStates Patent 3,651,696 REBNFQRCED LABHNATED SHEET Horace P. Fry, Jr.,West Chester, Pa, assignor to American Viscose Corporation, ihiiadelphia, Pa, a corporation of Delaware Filed Nov. 26, 1958, Ser. No.776,587 2 Claims. ((11. 156-229) RAYON Fannie herent extensibility ofthe fabric to a value approximating that of the sheet material.

The usual continuous filament viscose rayon yarn, unless highly twisted,has an extensibility of approximately 18% when dry and 22% when wetbefore its full strength is realized and the yarn breaks. This highextensibility can be considerably reduced, say to about 8% or even less,if during initial manufacture or subsequently, the yarn is subjected toa slashing operation wherein the yarn is wetted and then held undertension While drying. However, the reduced extensibility brought aboutby slashing is destroyed if the yarn is subsequently gotten Wet andallowed to dry in a relaxed or untensioned condition and consequentlyslashing is ordinarily only employed when the yarn is to be used in amanner wherein it is protected-from water, as for example, for tirecord.

Open-mesh fabric known as scrim, which may be either Woven or nonwoven,has a wide variety of uses. Obviously, in the case of non-woven scrim,the yarns making up the fabric must be secured together at theircrossing points in order to hold the fabric together and this iscustomarily accomplished by means of an adhesive. It is also customaryto employ an adhesive to secure the yarns together at their crossingpoints in woven scrim, especially in the case of Wide mesh scrim.Because the individual threads or yarns of scrim are not closelypackedtogether as they are in a closely woven fabric, the scrim has anextensibility substantially equal to that of individual yarns of whichit is formed. Thus, scrim formed of ordinary, unslashed, low-twistviscose rayon yarn has an extensibility of approximately 18% when dryand 22% when wet. Scrim formed of slashed rayon yarns has a much lowerextensibility but the adhesive employed must not contain water or beapplied as a Water emulsion or suspension unless the individual yarnsare maintained under tension until the fabric is completely dry forotherwise the low-extensibility characteristic of the yarn is destroyed,as mentioned above.

.While there are certain volatile adhesives which may be used which donot impair the low-extensibility of the yarn, these create undesirableand expensive Problems in connection with solvent recovery, ventilation,fire hazard, etc. On the other hand, when an aqueous adhesive liquid isemployed, the mechanisms necessary to maintain the yarn under tensionuntil dry are complicated and-the fabric-forming operation generally hasto proceed at a slower rate. While a'scrim of low extensibility isideally suited as'a reinforcing lamina for paper or other sheetmaterial, the above-mentioned problems in connection with forming thescrim of a low extensibility rayon yarn have limited its use for thispurpose. This use has been further restricted by the necessity foremploying volatile, non-aqueous adhesives when laminating the scrim tothe paper.

ass sts Patented Aug. 28, 1962 'ice It is an object of the presentinvention to provide an improved method of laminating an open-mesh rayonfabric to a sheet of paper or like material in such manner that thefabric will have an extensibility substantially equal to that of thematerifl to which it is laminated whereby the composite sheet will havea breaking strength substantially equal to the combined breakingstrengths of the fabric and the material to which it is laminated.

It is a further object of this invention to provide a method oflaminating an open-mesh rayon fabric to a sheet of another material insuch manner that the fabric and the sheet to which it is laminated willhave substantially the same extensibility and wherein the fabric isformed of ordinary unstrained rayon yarn.

It is a still further object of this invention to permit a highlyextensible rayon yarn to be used for forming a fabric which issubsequently used as a reinforcing lamina for sheet material.

Another object of the invention is to provide a laminating techniquewhich permits the use of an aqueous adhesive liquid for reinforcablyadhering an open-mesh rayon fabric to a sheet of paper.

Still another object is to provide a method of reinforcing variousflexible sheet materials with an openmesh rayon fabric which permitsordinary unstrained yarn to be used to form the fabric to thus effectsubstantial economy in manufacture.

Other and further objects, features and advantages of the invention willbecome apparent as the description thereof proceeds.

Referring now to the drawing:

FIGURE 1 is a plan view of a form of apparatus suitable for use inpracticing the invention; and

FIGURE 2 is a side elevational View of the apparatus.

In the drawing, the scrim, an open-mesh woven or non-woven fabric, isindicated at 19 and two lengths of sheet material such as paper or thelike, between which the scrim is to be laminated, are indicated at 11and 12. Methods and apparatus for manufacturing scrim are well known inthe art and need not be described herein but it is to be noted that inaccordance with this invention, it may be formed of ordinary,unstrained, continuous filament, low twist viscose rayon yarn and infact in order to obtain the full advantage of this invention it ispreferably formed of such yarn. However, certain advantages of thepresent invention may be realized when the scrim is formed of so-calledhigh tenacity yarn, that is to say, yarn which has been dried withoutallowing it to shrink so as to reduce the extensibility thereof and itis therefore within the purview of the invention to form the scrim ofthis type of yarn.

As previously noted, the ordinary, unstrained rayon yam has anextensibility of approximately 18% when dry and the scrim formed of suchyarn has a like degree of extensibility. In order for the scrim toeffectively reinforce the paper or other material with which it islaminated, it is necessary that the extensibility of the scrim and thepaper be substantially the same so that when a strain is applied to thelaminated "structure the full combined strength of both materials may berealized before either breaks. Now the paper or other material 11 and 12will normally have very considerably less extensibility than the scrimand according to the present invention the extensibilities of the twomaterials are equalized by stretching the scrim, wetting it and dryingit under tension to reduce the extensibility of the scrim to that of thepaper. For example, assuming that the paper is capable of stretching 4%before bursting; the scrim, if it inherently has 18% extensibility willbe stretched 14%, wetted and dried Without allowing it to shrink andthereafter so long as it remains dry it will have an extensibility ofonly 4%. It will be understantially eqpal 'tothat of thepaper. V o p 7 Va A {creped laminated sheet can be made by the process stood that thesepercentages are used only by way of example and that according to theteaching of this inoriginal size and in doing so will crinkle or crepethe 7 paper in all directions. Because of the creping, the exvention itis necessary to determine the actual inherenttensibility of the paper isgreatly increased so that the extensibility of the paper and thescrimare substantially the same. V a A creped laminated sheet may alsobe made by using a scrim formed from ayarn havingsubstantially the sameextensibility ,as that of the sheets with which it is s laminated. Inthis case the scrim is' not stretched but rollers are driven at a speedsufficiently faster than the speed of the roll from which the scrim isbeing Withdrawn so that the desired amount of stretch is imparted to thescrim in its longitudinal direction. A'pair of nip plates and 16 aresecured to angularly arranged shafts 17 and 18 respectively, located atone side of the scrim and a similar arrangement of nipplates generallyindicated at 19 is mounted at the opposite side of the scrim.

V The opposite edges of the scrim are directed between the respectivepairs of nip plates so that as'the'scrim is pulled "forward by the feedrollers l3 and 14 the 'opposite edges thereof are grasped by the nipplates which are rotated ina direction and at a speed totransverselystretch the scrim to the predetermined extent equal. to

the longitudinal stretch. V

The two sheets of paper 11 and 12 are directed between the feed rollers13 and 14 so as to be pulled forward thereby but they are fed from theirsource at the same speed that they are pulled forward so that there isno stretching of the paper. Spray nozzles 20 and 21 are provided for'spraying an aqueous adhesive liquid onto 14. The feed rolls extend forat least the width of the j paper sheets so as to hold the scrim in itsstretched condition after it is passed beyond the nip plates.

' The water in the adhesive liquid 'rnoistens the scrim? sufi icientlythat it willretain its increased size and reduced extensibility if heldtaut until dry. A series of heated pressure drying rolls 22 are locatedbeyond the feed rollers 13 14 and the sheets of paper and the scrim areheld tightly pressedrtogether as they pass around and between the rolls22 as shown in FIGURE is merely fed through the feed rollers Band 14between the other sheets. Of course, the scrim itself will originally beof the same width as theother'two sheets. An aqueous adhesive solutionisused so that the scrim will have a strong tendency to shrink.-However, the scrim is held taut by the feed rollers 13 and 14 and thepressure dryer $011522 so that it cannot shrink to an appreciableextent' and its extensibility is therefore substantialiyunchanged.However, unless the paper isespecially sun the scrim will shrink to asmall degree and in doing .so will crepe the paper in all directions.

Of 'course, in any of the examples :hereinbefore referred to, the scrimneed not be located between two sheets but may be adhered to one or bothsides of a single sheetof paper or the like.

Having thus described several methods embodying the inventive concept,what is claimed is: I

l. The method of making a rayon fabric reinforced laminated paper,comprising stretching an open-mesh fabric formed of unstrained rayonyarn having a substantial degree of extensibility to the extent that theindividual yarns of the fabric are elongated to the point where theirremaining extensibility is approximately equal to the extensibility'ofthe paper with which the fabric is to be laminated, applyingan aqueousadhesive to one face of each of twosheets of paper, introducing thefabric while in the above mentioned stretched condition between theadhesive coated faces of the sheetsof paper whereby the fabric is wettedby the aqueous adhesive, and drying the adhesive and the fabric whilemaintaining the fabric in the stretched condition whereby the individualrayon yarns retain their elongation so long as :they remain dry to thusproduce --a rayon fabric reinforced paper wherein the fabric and'thepaper have approximately the same extensibility.

2. Afterleaving the rolls 22 the now laminated. sheet V 23 may be woundinto a roll. The laminated sheet 23 fthus'comprises twosheets of paperor the like inherent- V lyhaving a reasonably' low extensibility betweenwhich i is :adhered the scrim which now has anextensibility subof thisinvention-and this is most advantageouslyaccomfplished by using a scrimmade-from slashed hava transversely. to an extent where its remainingextensi V bility 'isv snbstantially equal tothatof the paper or thelike, but instead of using an aqueous adhesiveliquid a 'nated isespecially strong, the scrim will return to its non-aqueous adhesivesuch as asphalt may be employed.

As the scrim. and the paper passaround'and between the rollers22, thea'sphalt causes the scrim to adhere to: the paper but sincegno water isappliedto the scrim jit will xhavela strong ftendency'to return to "itsoriginal dimen- I sions after passing through the rolls 22"and un1essthe .paper or other material between which the scrim is lami V 2. Themethod of making a rayon'fabric reinforced laminated paper, comprisingstretching an open-mesh fabric formed of unstrained rayon yarn having asubstantial degree 'of extensibility tothe. extent that the individualyarns of the fabric are elongated to the point where their remainingextensibility: is approximately equal to the extensibility of the paperwith which the fabric is ;to be laminated, applying an'aqueous adhesiveto one faceof each of twjo sheets of paper, introducing the fabric whilein the above mentioned. stretched conditionbetween the adhesive coatedfaces of thejsh eets of paper whereby the fabric is 'wetted' bythe-aqueous adhesive 'and applying heat and pressure to'the outer facesof the sheets of paper to dry the adhesive and the fabric and maintainthe fabric in the stretched condition during the drying whereby theindividual rayon yarns of the fabric retain their elongation to thusproduce a rayon fabric reinforcedpaper wherein the fabric and the'paperhave approximately the same extensibility.

References Citefd inthe file of this patent V UNITED STATES rAT N'rs2,503,024 Boese et al. V Apr. .4, 195.0 2,575,666 Knudson ,V. V Nov. 20,1951 2,674,555 Pahl etal. ';.i Apr. 6, 1954 i OR I P NT 438,786 a GreatBritain Nov. 21, 1935 Australia ..V Oct; 29, 1952

1. THE METHOD OF MAKING A RAYON FABIC REAINFORCED LAMINATED PAPER,COMPRISING STRAETCHING AN OPEN-MESH FABIC FORMED OF UNSRAINED RAYON YARNHAVING A SUBSTANTIALLY DEGREE OF EXTENSIBILITY TO THE EXTEN THAT THEINDIVIDUAL YARNS OF THE FABRIC ARE ELONGATED TO THE POINT WHERE THEIRREMAINING EXTENSILILITY IS APPROXIMATELY EQUAL TO THE EXTENSIBILITY OFTHE PAPER WITH WHICH THE FABRIC IS TO BE LAMINATED, APPLYING AN AQUEOUSADHESIVE TO ONE FACE OF EACH OF TWO SHEETS OF PAPER, INTRODUCING THEFABRIC WHILE IN THE ABOVE MENTIONED STRETCHED CONDITION BETWEEN THEADHESIVE COATED FACES OF THE SHEETS OF PAPER WHEREBY THE FABRIC ISWETTING BY THE AQUEOUS ADHESIVE, AND DRYING THE ADHESIVE AND THE FABRICWILE MAINTAINING THE FABRIC IN THE STRETCHED CONDITION WHEREBY THEINDIVIDUAL RAYON YARNS RETAIN THEIR ALONGATION SO LONG AS THEY REMAINDRY TO THUS PRODUCE A RAYON FABRIC REINFORCED PAPER WHEREIN THE FABRICAND THE PAPER HAVE APPROXIMATELY THE SAME EXTENSIBILITY.